1. Field of the Invention
The present invention relates to an ink jet-type printer apparatus which jets ink droplet onto a print medium and, more particularly, to an ink jet-type printer control having an ink purging function for evacuating vaporized ink and dried ink from nozzles of a printer head to restore desired ink jetting operation of the nozzles.
2. Description of Related Art
It is known in a conventional ink jet-type printer apparatus to use an ink purging device which covers the nozzle forming surface of a printer head by an evacuation cap and evacuates the undesired or degraded ink from nozzles by vacuuming the inside space of the evacuation cap by a pump.
When a used ink cartridge coupled with the printer head are exchanged for a new one, it occurs that air enters into an ink supply passage connecting the ink cartridge and the printer head. This air is likely to admix with the ink in the ink supply passage and become bubbles. Further, gas produced in the ink through adhesives between manifold members providing the ink supply passage becomes bubbles in the ink. The bubbles in the ink grow bigger as time passes. As the bubbles are bigger and the number increases more, more ink must be evacuated to eliminate such bubbles.
The printer head may be covered by a capping device to restrict drying of the ink when the printer apparatus is not in use. Even in this instance, the ink will become dried gradually as time passes resulting in degradation of ink.
The conventional ink purging device is designed to perform the evacuation operation a fixed number of times irrespective of the time period for which the printer apparatus is not used. Therefore, the bubbles in the ink and the dried ink may not be evacuated unless the evacuation is performed timely. As a result, there will occur that the required ink jetting operation cannot be restored by the fixed number of evacuation operations or that the ink may be wastefully evacuated if the purging is performed too frequently.